diff --git a/browser/base/content/test/performance/StartupContentSubframe.sys.mjs b/browser/base/content/test/performance/StartupContentSubframe.sys.mjs
index a7e89bba997d..ac568312c0af 100644
--- a/browser/base/content/test/performance/StartupContentSubframe.sys.mjs
+++ b/browser/base/content/test/performance/StartupContentSubframe.sys.mjs
@@ -32,9 +32,6 @@ export class StartupContentSubframeChild extends JSWindowActorChild {
     let collectStacks = AppConstants.NIGHTLY_BUILD || AppConstants.DEBUG;
 
     let modules = new Map();
-    for (let module of Cu.loadedJSModules) {
-      modules.set(module, collectStacks ? Cu.getModuleImportStack(module) : "");
-    }
     for (let module of Cu.loadedESModules) {
       modules.set(module, collectStacks ? Cu.getModuleImportStack(module) : "");
     }
diff --git a/browser/base/content/test/performance/browser_startup_content.js b/browser/base/content/test/performance/browser_startup_content.js
index a80458a2fd4c..3a9f858b2f41 100644
--- a/browser/base/content/test/performance/browser_startup_content.js
+++ b/browser/base/content/test/performance/browser_startup_content.js
@@ -125,12 +125,6 @@ add_task(async function () {
         );
         let collectStacks = AppConstants.NIGHTLY_BUILD || AppConstants.DEBUG;
         let modules = new Map();
-        for (let module of Cu.loadedJSModules) {
-          modules.set(
-            module,
-            collectStacks ? Cu.getModuleImportStack(module) : ""
-          );
-        }
         for (let module of Cu.loadedESModules) {
           modules.set(
             module,
diff --git a/browser/components/StartupRecorder.sys.mjs b/browser/components/StartupRecorder.sys.mjs
index 8fb8f834473e..ac6fcf20c9ab 100644
--- a/browser/components/StartupRecorder.sys.mjs
+++ b/browser/components/StartupRecorder.sys.mjs
@@ -105,7 +105,7 @@ StartupRecorder.prototype = {
       name
     );
     this.data.code[name] = {
-      modules: Cu.loadedJSModules.concat(Cu.loadedESModules),
+      modules: Cu.loadedESModules,
       services: Object.keys(Cc).filter(c => {
         try {
           return Cm.isServiceInstantiatedByContractID(c, Ci.nsISupports);
diff --git a/js/xpconnect/tests/unit/test_loadedESModules.js b/js/xpconnect/tests/unit/test_loadedESModules.js
index 00e10590370e..3ab962b58453 100644
--- a/js/xpconnect/tests/unit/test_loadedESModules.js
+++ b/js/xpconnect/tests/unit/test_loadedESModules.js
@@ -1,78 +1,8 @@
-add_task(function test_JSModule() {
-  const URL1 = "resource://test/jsm_loaded-1.jsm";
-  const URL2 = "resource://test/jsm_loaded-2.jsm";
-  const URL3 = "resource://test/jsm_loaded-3.jsm";
-
-  Assert.ok(!Cu.loadedJSModules.includes(URL1));
-  Assert.ok(!Cu.isJSModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedJSModules.includes(URL2));
-  Assert.ok(!Cu.isJSModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedJSModules.includes(URL3));
-  Assert.ok(!Cu.isJSModuleLoaded(URL3));
-  Assert.ok(!Cu.loadedESModules.includes(URL1));
-  Assert.ok(!Cu.isESModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedESModules.includes(URL2));
-  Assert.ok(!Cu.isESModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedESModules.includes(URL3));
-  Assert.ok(!Cu.isESModuleLoaded(URL3));
-
-  ChromeUtils.import(URL1);
-
-  Assert.ok(Cu.loadedJSModules.includes(URL1));
-  Assert.ok(Cu.isJSModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedJSModules.includes(URL2));
-  Assert.ok(!Cu.isJSModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedJSModules.includes(URL3));
-  Assert.ok(!Cu.isJSModuleLoaded(URL3));
-  Assert.ok(!Cu.loadedESModules.includes(URL1));
-  Assert.ok(!Cu.isESModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedESModules.includes(URL2));
-  Assert.ok(!Cu.isESModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedESModules.includes(URL3));
-  Assert.ok(!Cu.isESModuleLoaded(URL3));
-
-  ChromeUtils.import(URL2);
-
-  Assert.ok(Cu.loadedJSModules.includes(URL1));
-  Assert.ok(Cu.isJSModuleLoaded(URL1));
-  Assert.ok(Cu.loadedJSModules.includes(URL2));
-  Assert.ok(Cu.isJSModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedJSModules.includes(URL3));
-  Assert.ok(!Cu.isJSModuleLoaded(URL3));
-  Assert.ok(!Cu.loadedESModules.includes(URL1));
-  Assert.ok(!Cu.isESModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedESModules.includes(URL2));
-  Assert.ok(!Cu.isESModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedESModules.includes(URL3));
-  Assert.ok(!Cu.isESModuleLoaded(URL3));
-
-  ChromeUtils.import(URL3);
-
-  Assert.ok(Cu.loadedJSModules.includes(URL1));
-  Assert.ok(Cu.isJSModuleLoaded(URL1));
-  Assert.ok(Cu.loadedJSModules.includes(URL2));
-  Assert.ok(Cu.isJSModuleLoaded(URL2));
-  Assert.ok(Cu.loadedJSModules.includes(URL3));
-  Assert.ok(Cu.isJSModuleLoaded(URL3));
-  Assert.ok(!Cu.loadedESModules.includes(URL1));
-  Assert.ok(!Cu.isESModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedESModules.includes(URL2));
-  Assert.ok(!Cu.isESModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedESModules.includes(URL3));
-  Assert.ok(!Cu.isESModuleLoaded(URL3));
-});
-
 add_task(function test_ESModule() {
   const URL1 = "resource://test/es6module_loaded-1.sys.mjs";
   const URL2 = "resource://test/es6module_loaded-2.sys.mjs";
   const URL3 = "resource://test/es6module_loaded-3.sys.mjs";
 
-  Assert.ok(!Cu.loadedJSModules.includes(URL1));
-  Assert.ok(!Cu.isJSModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedJSModules.includes(URL2));
-  Assert.ok(!Cu.isJSModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedJSModules.includes(URL3));
-  Assert.ok(!Cu.isJSModuleLoaded(URL3));
   Assert.ok(!Cu.loadedESModules.includes(URL1));
   Assert.ok(!Cu.isESModuleLoaded(URL1));
   Assert.ok(!Cu.loadedESModules.includes(URL2));
@@ -82,12 +12,6 @@ add_task(function test_ESModule() {
 
   ChromeUtils.importESModule(URL1);
 
-  Assert.ok(!Cu.loadedJSModules.includes(URL1));
-  Assert.ok(!Cu.isJSModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedJSModules.includes(URL2));
-  Assert.ok(!Cu.isJSModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedJSModules.includes(URL3));
-  Assert.ok(!Cu.isJSModuleLoaded(URL3));
   Assert.ok(Cu.loadedESModules.includes(URL1));
   Assert.ok(Cu.isESModuleLoaded(URL1));
   Assert.ok(!Cu.loadedESModules.includes(URL2));
@@ -97,12 +21,6 @@ add_task(function test_ESModule() {
 
   ChromeUtils.importESModule(URL2);
 
-  Assert.ok(!Cu.loadedJSModules.includes(URL1));
-  Assert.ok(!Cu.isJSModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedJSModules.includes(URL2));
-  Assert.ok(!Cu.isJSModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedJSModules.includes(URL3));
-  Assert.ok(!Cu.isJSModuleLoaded(URL3));
   Assert.ok(Cu.loadedESModules.includes(URL1));
   Assert.ok(Cu.isESModuleLoaded(URL1));
   Assert.ok(Cu.loadedESModules.includes(URL2));
@@ -112,12 +30,6 @@ add_task(function test_ESModule() {
 
   ChromeUtils.importESModule(URL3);
 
-  Assert.ok(!Cu.loadedJSModules.includes(URL1));
-  Assert.ok(!Cu.isJSModuleLoaded(URL1));
-  Assert.ok(!Cu.loadedJSModules.includes(URL2));
-  Assert.ok(!Cu.isJSModuleLoaded(URL2));
-  Assert.ok(!Cu.loadedJSModules.includes(URL3));
-  Assert.ok(!Cu.isJSModuleLoaded(URL3));
   Assert.ok(Cu.loadedESModules.includes(URL1));
   Assert.ok(Cu.isESModuleLoaded(URL1));
   Assert.ok(Cu.loadedESModules.includes(URL2));
diff --git a/toolkit/components/backgroundtasks/tests/browser/browser_xpcom_graph_wait.js b/toolkit/components/backgroundtasks/tests/browser/browser_xpcom_graph_wait.js
index 17379407697c..4e31976dacf9 100644
--- a/toolkit/components/backgroundtasks/tests/browser/browser_xpcom_graph_wait.js
+++ b/toolkit/components/backgroundtasks/tests/browser/browser_xpcom_graph_wait.js
@@ -200,7 +200,7 @@ add_task(async function test_xpcom_graph_wait() {
 
   function newMarkers() {
     return {
-      // The equivalent of `Cu.loadedJSModules` + `Cu.loadedESModules`.
+      // The equivalent of `Cu.loadedESModules`.
       modules: [],
       services: [],
     };
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js b/toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js
index c8632f22f06d..ac461e57c63c 100644
--- a/toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_startup_perf.js
@@ -58,9 +58,9 @@ add_task(async function test_loaded_scripts() {
     "No extra APIs should be loaded at startup for a simple extension"
   );
 
-  let loadedModules = Cu.loadedJSModules
-    .concat(Cu.loadedESModules)
-    .filter(url => url.startsWith("resource://gre/modules/Extension"));
+  let loadedModules = Cu.loadedESModules.filter(url =>
+    url.startsWith("resource://gre/modules/Extension")
+  );
 
   deepEqual(
     loadedModules.sort(),